/*
 * Copyright (c) 2011-2012 Alexander Dubu
 * All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions are met:
 *
 * o  Redistributions of source code must retain the above copyright notice,
 *    this list of conditions and the following disclaimer.
 *
 * o  Redistributions in binary form must reproduce the above copyright notice,
 *    this list of conditions and the following disclaimer in the documentation
 *    and/or other materials provided with the distribution.
 *
 * o  Neither the name Axil nor the names of its contributors may be used to
 *    endorse or promote products derived from this software without specific
 *    prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
 * AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
 * ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE
 * LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
 * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
 * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
 * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
 * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
 * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
 * POSSIBILITY OF SUCH DAMAGE.
 */

package axil.stdlib.numbers.operator;

import axil.api.AxilObject;
import axil.api.extend.Operator;
import axil.stdlib.core.type.Nil;
import axil.stdlib.numbers.type.FloatingPoint;
import axil.stdlib.numbers.type.Int;
import axil.stdlib.numbers.type.Num;

import static axil.framework.Functions.*;


/**
 * Perform an exponentiation operation on the value.
 */
public class Exponent implements Operator {
	/**
	 * Execute this operator with the given operands. The given operands have
	 * already been evaluated. If this operation does not make sense for the
	 * given operands, then an exception is thrown.
	 *
	 * @param left
	 * 	The left operand, which can be any Axil object. The value given is
	 * 	never null but may be the nil object (Axil.NIL).
	 *
	 * @param right
	 * 	The left operand, which can be any Axil object. The value given is
	 * 	never null but may be the nil object (Axil.NIL).
	 *
	 * @return
	 * 	Returns any Axil object, but not null.
	 */
	public AxilObject eval(AxilObject left, AxilObject right) {
		Num na;
        Num nb;
        try {
            if (nil(left, right)) {
                return Nil.object;
            }
            na = num(left);
            nb = num(right);
        } catch (ClassCastException e) {
            throw error(axil(), "invalid-operand",
                    nv("operator", "^"), nv("type", left.type().identity()));
        }
		if (nb instanceof Int) {
			int v = ((Int)nb).value();
			if (v <= 3) {
				Num r = na;
				for (int i = 1; i < v; i++) {
					r = r.multiply(na);
				}
				return r;
			}
		}
		double r = Math.pow(na.fp(), nb.fp());
        FloatingPoint fp = new FloatingPoint(r);
        return fp.as(Math.max(na.kind(), nb.kind()));
	}
}
